Issues with undefined index in php/mysql - php

Question

I hope that I describe my problem properly. I have created a database for a cafeteria. This has the following tables: orders, members ISA manager and servers, products and categories. In the table orders I should insert features such as title,quantity,datetime,sum and user name of the corresponding server. I've managed to do so via php in my files posted before in this forum (follow the link: Insert data from textbox and checkbox into database ).
The web environment so far is consisted of :
a)index.php, members.php (these files are responsible for the login and the authentication of any kind of user, either the administrator or serves.
b)addorder_form.php and addorder.php as far the order form and the insert of the order details in database.
I cannot make my system print the username of each server for each order.
I tried something like this but I 've got the error of undefined index username :
<?php
session_start();
include_once("buzzcafe_fns.php");
include_once("members.php");
do_html_header("");
$conn = mysql_connect("localhost", "root", "");
$db=mysql_select_db("buzzcafe" ,$conn);
db_connect();
if (isset($_SESSION['username']){
if (isset($_POST['products'])) {
if (isset($_POST['quantity'])) {
foreach($_POST['products'] as $key => $products){
$quantity = isset($_POST['quantity'][$key])? $_POST['quantity'][$key]:'Not selected';
date_default_timezone_set('Europe/Athens');
$date = date('Y-m-d H:i:s');
$message[] = $products.' - x'.$quantity;
$insertOrder = mysql_query("INSERT INTO orders (datetime,title,quantity,username) VALUES('".$date."','".$products."','".$quantity."', '".$_SESSION['username']."')")or die(mysql_error());
echo $_SESSION['username'];
}
}
echo implode(',', $message);
echo "<br/>";
echo "<br />Record inserted";
echo "<br/>";
echo $date;
}
else { echo "You did not choose a quantity."; }
}else { echo "You did not choose any product."; }
}
?>
Why is username undefined?
A part of members.php:
<?php
if (isset($_POST['username']) && isset($_POST['password'])) {
$username = $_POST['username'];
$password = $_POST['password'];
if ((!$username) || (!$password)) {
do_html_header('');
echo '<h3 style="color:#800000;">Please fill in both fields</h3><br><br></br></br>';
display_login_form();
}
else {
$sql = mysql_query('SELECT * FROM members WHERE username="'.$_POST['username'].'" AND password=sha1("'.$_POST['password'].'")') or die(mysql_error());
$login_check_member = mysql_num_rows($sql);
if($login_check_member > 0) {
while($row = mysql_fetch_array($sql)) {
$role = $row["role"];
$_SESSION['role'] = $role;
$us = $row["username"];
$_SESSION['username'] = $us;
$username = $_SESSION['username'];
}
}
I include this file in my addorder.php file.

Answer 1

Probably because it's not defined?
Seems people are a little more concerned about your SQL than anything -- but this may help you in the actual question.
Throw this in there before them nested conditions:
if (defined($_SESSION['username'])) {
echo 'Username is defined!';
}
else {
die('Username is undefined!');
}